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Subject-Verb Agreement

70 questions

All types70Multiple choice37Fill in the blank33
Question 41Question →

The following passage is an excerpt from a science article:

Deep-sea hydrothermal vents, first discovered in 1977, support unique ecosystems that thrive in the absence of sunlight. The biological diversity of these remote habitats, which includes giant tube worms and ghost crabs, depend on chemosynthetic bacteria for survival. These microorganisms convert toxic hydrogen sulfide into organic matter, forming the foundation of the vent food web.

Which option is the grammatically correct replacement for the underlined word?

Show answer & explanation

Answer: depends

Answer

The option containing the singular present-tense verb 'depends' is correct.
The grammatical subject of the sentence is 'diversity,' which is singular. The prepositional phrase 'of these remote habitats' and the relative clause 'which includes giant tube worms and ghost crabs' are intervening descriptive elements that do not affect the grammatical number of the subject. Therefore, a singular verb is required. The present-tense singular verb 'depends' matches the subject and maintains the present-tense context of the surrounding sentences.

Step-by-Step Solution

1
Identify the true subject of the verb in the underlined portion.
The subject is the singular noun 'diversity.'
To ensure subject-verb agreement, the subject must be isolated from intervening elements. Here, 'of these remote habitats' (prepositional phrase) and 'which includes giant tube worms and ghost crabs' (relative clause) contain plural nouns, but they do not change the singular nature of the subject 'diversity.'
2
Determine the appropriate verb form based on subject number and tense consistency.
The singular, present-tense verb 'depends' is required.
A singular subject requires a singular verb. Furthermore, the passage is written in the present tense ('support,' 'convert,' 'forming'), meaning the present-tense form 'depends' must be used to maintain tense consistency.

Key Concept

Subject-Verb Agreement with Intervening Phrases
Question 42Question →

Read the following passage about meteorology. Which present-tense form of the verb 'depend' correctly completes the sentence to maintain subject-verb agreement?

Fill in the blanks below

The formation of supercell thunderstorms, which can produce devastating tornadoes and large hail, on strong vertical wind shear and high atmospheric instability.
Show answer & explanation

Answer

depends
The subject of the sentence is 'formation', which is singular. The plural nouns 'thunderstorms', 'tornadoes', and 'hail' are part of intervening prepositional phrases and relative clauses, so they do not affect the verb agreement. Therefore, the singular present-tense verb 'depends' is the correct choice.

Step-by-Step Solution

1
Identify the subject of the sentence.
The subject of the sentence is the singular noun 'formation'.
To ensure subject-verb agreement, we must first locate the noun that is performing the action, bypassing any intervening descriptive phrases.
2
Analyze intervening phrases and clauses.
The prepositional phrase 'of supercell thunderstorms' and the relative clause 'which can produce devastating tornadoes and large hail' modify 'formation' but do not change its singular number.
Plural nouns within modifying phrases (such as 'thunderstorms' and 'tornadoes') can easily distract from the true singular subject.
3
Match the singular subject with the correct verb form.
A singular subject requires a singular present-tense verb: 'depends'.
Singular verbs in the present tense end with an 's' (depends), whereas plural verbs do not (depend).

Key Concept

Subject-Verb Agreement with Intervening Phrases
Estimated Time:1m 0s
Question 43Question →

Read the passage below and fill in the blank with the correct present-tense form of the verb 'reveal' that agrees with its subject.

Fill in the blanks below

The exploration of deep caves, often referred to as speleology, presents unique challenges to scientists. A team of researchers studying the subterranean microclimates in these caves must carry specialized instrumentation. Each of the rock samples collected from the deepest caverns a distinct chemical composition that helps scientists date the cave's formation.
Show answer & explanation

Answer

reveals
The correct verb form is 'reveals' because the subject of the clause is 'Each', a singular indefinite pronoun. The prepositional phrase 'of the rock samples collected from the deepest caverns' contains plural nouns, but it does not change the singular nature of the subject. A singular subject requires a singular present-tense verb.

Step-by-Step Solution

1
Identify the subject of the sentence containing the blank.
The subject is the indefinite pronoun 'Each'.
The phrase 'of the rock samples collected from the deepest caverns' is a prepositional phrase modifying the pronoun 'Each' and does not affect the number of the verb.
2
Determine the grammatical number of the subject 'Each'.
The pronoun 'Each' is singular.
Indefinite pronouns such as 'each', 'either', and 'neither' are grammatically singular and require singular verbs.
3
Select the correct present-tense verb form of 'reveal' that agrees with the singular subject.
The singular present-tense form is 'reveals'.
Singular verbs in the present tense end with 's', whereas plural verbs do not.

Key Concept

Subject-Verb Agreement with Intervening Phrases
Estimated Time:1m 0s
Question 44Question →

The passage below is from an essay about early audio preservation.

Early sound recordings captured on wax cylinders in the late nineteenth century offer a fragile window into the past. The physical degradation of these delicate artifacts, which are prone to mold growth and scratches, demands advanced laser scanning technologies to recover the audio without touching the surface. Indeed, the preservation of such rare recordings represent a race against time.

Which of the following is the best revision of the bolded word "represent" in the passage?

Show answer & explanation

Answer: represents

Answer

represents
The subject of the sentence is the singular noun 'preservation,' not the plural noun 'recordings' inside the intervening prepositional phrase 'of such rare recordings.' Therefore, the verb must be singular. The present-tense singular verb 'represents' correctly agrees with the subject and maintains consistency with the present-tense verbs used throughout the passage.

Step-by-Step Solution

1
Identify the subject of the verb in the final sentence.
The subject of the verb is the singular noun 'preservation.' The prepositional phrase 'of such rare recordings' is an intervening modifier and does not affect the subject's grammatical number.
A verb must agree in number with its grammatical subject, not with the noun in any intervening prepositional phrase.
2
Determine the appropriate tense of the verb based on the passage context.
The other verbs in the passage ('offer', 'are', 'demands') are in the present tense, indicating that the verb in the final sentence should also be in the present tense.
Verb tenses must remain consistent throughout a passage unless there is a logical reason to shift tenses.
3
Select the option that provides the present-tense singular form of the verb.
The verb form 'represents' is both singular and in the present tense, matching the singular subject 'preservation.'
This form resolves the subject-verb agreement error while maintaining tense consistency.

Key Concept

Subject-Verb Agreement
Estimated Time:1m 0s
Question 45Question →

The restoration of mid-century modern furniture, which often involves sourcing rare veneer and period-correct hardware, requires a high level of patience. A specialized set of chisels and scrapers are essential for removing old finish without damaging the underlying wood.

Which of the following options is the correct way to write the underlined portion of the sentence?

Show answer & explanation

Answer: is

Answer

The correct answer is 'is'. The singular subject 'set' requires the singular verb 'is', and the present tense must be maintained to match the surrounding context.
The correct option is 'is' because the subject of the verb is the singular noun 'set'. The prepositional phrase 'of chisels and scrapers' contains plural nouns but does not affect the number of the subject. Additionally, the present-tense form 'is' maintains consistency with the present-tense verb 'requires' in the first sentence.

Step-by-Step Solution

1
Identify the subject of the clause containing the underlined verb.
The subject is the noun phrase 'A specialized set of chisels and scrapers', where the head noun is the singular noun 'set'.
To ensure subject-verb agreement, the verb must match the number of the head noun, not the nouns in the intervening prepositional phrase.
2
Determine the correct tense based on the context of the passage.
The first sentence uses the present-tense verb 'requires', indicating that the passage is written in the present tense. Thus, the verb must be in the present tense.
Consistent verb tense must be maintained throughout the passage to avoid illogical shifts.
3
Evaluate the choices to find the singular, present-tense verb.
The form 'is' is singular and present tense, which fits both requirements. 'NO CHANGE' (which is 'are') is plural, 'was' is past tense, and 'were' is plural and past tense.
Only 'is' resolves the agreement error without introducing a tense shift.

Key Concept

Subject-Verb Agreement with Intervening Phrases
Estimated Time:45s
Question 46Question →

The sentence below is about maritime archaeology. Which present-tense form of the verb 'allow' correctly completes the sentence to ensure proper subject-verb agreement?

Fill in the blanks below

The preservation of ancient wooden shipwrecks, which are often found in deep, oxygen-depleted waters, researchers to reconstruct historical trade routes with remarkable accuracy.
Show answer & explanation

Answer

allows
The singular subject 'preservation' requires the singular present-tense verb 'allows.' The plural nouns 'shipwrecks' and 'waters' are located within modifying phrases that separate the subject from the verb, meaning they do not affect the agreement.

Step-by-Step Solution

1
Identify the true grammatical subject of the sentence.
The subject is the singular noun 'preservation.'
The prepositional phrase 'of ancient wooden shipwrecks' and the relative clause 'which are often found in deep, oxygen-depleted waters' serve as intervening modifiers and do not determine the singular or plural status of the verb.
2
Determine the correct verb form that agrees with the singular subject.
The singular present-tense form 'allows' is required.
A singular subject ('preservation') requires a singular verb form ('allows') to maintain proper subject-verb agreement.

Key Concept

Subject-Verb Agreement with Intervening Phrases
Question 47Question →

The monumental Arch of Constantine, which stands near the Colosseum and features reliefs repurposed from earlier imperial monuments, celebrate the victory of Constantine I over Maxentius. Many modern historians analyze these architectural choices as deliberate political propaganda.

Which choice best completes the underlined portion of the sentence?

Show answer & explanation

Answer: celebrates

Answer

celebrates
The singular subject is 'Arch', which requires a singular verb. The correct verb form is the singular present-tense 'celebrates'. This matches the tense of the surrounding verbs ('stands', 'features', and 'analyze') and correctly maintains subject-verb agreement.

Step-by-Step Solution

1
Locate the main subject of the clause containing the underlined verb.
The subject is the singular noun 'Arch'.
Intervening descriptions, such as the relative clause 'which stands near the Colosseum and features reliefs repurposed from earlier imperial monuments,' must be set aside to determine the true subject.
2
Check the tense of the surrounding context.
The other verbs in the passage, including 'stands', 'features', and 'analyze', are in the present tense.
Maintaining consistent verb tense is necessary unless there is a clear logical reason to shift tenses.
3
Select the verb form that matches the singular subject in the present tense.
The correct verb form is the singular present-tense 'celebrates'.
This maintains both subject-verb agreement and temporal consistency across the sentences.

Key Concept

Subject-Verb Agreement with Intervening Clauses
Estimated Time:45s
Question 48Question →

In the paragraph below, which present-tense form of the verb 'indicate' correctly completes the sentence to maintain proper subject-verb agreement?

Fill in the blanks below

The annual migration of monarch butterflies, which spans thousands of miles from North America to central Mexico, a remarkable capacity for navigation.
Show answer & explanation

Answer

indicates
The correct verb form is the singular present-tense 'indicates'. The grammatical subject of the sentence is the singular noun 'migration'. The plural nouns 'butterflies' and 'miles' are part of intervening prepositional and relative clauses and do not affect the singular number of the subject.

Step-by-Step Solution

1
Locate the grammatical subject of the clause containing the blank.
The subject is the singular noun 'migration'.
The prepositional phrase 'of monarch butterflies' and the relative clause 'which spans thousands of miles...' are intervening modifiers that do not change the number of the subject.
2
Determine the correct verb form that agrees in number with the subject.
The singular verb form 'indicates' is required to agree with the singular subject 'migration'.
In the present tense, singular subjects require verbs ending in '-s', whereas plural subjects require the base form without '-s'.

Key Concept

Subject-Verb Agreement with Intervening Modifiers
Question 49Question →

Historically, the cultivation of heirloom crops, which preserves genetic diversity and offers unique flavor profiles, have gained popularity among modern organic farmers.

Which choice correctly completes the underlined portion of the sentence to maintain proper subject-verb agreement?

Show answer & explanation

Answer: has gained

Answer

The correct option is 'has gained' because it is a singular verb that agrees with the singular subject 'cultivation'.
The singular verb 'has gained' agrees with the singular subject 'cultivation'. The plural noun 'crops' and the intervening relative clause do not affect the singular status of the main subject.

Step-by-Step Solution

1
Identify the true subject of the main clause.
The subject of the main verb is 'cultivation'.
The singular noun 'cultivation' is the head of the subject phrase. The subsequent plural noun 'crops' is object of the preposition 'of', and the relative clause starting with 'which' merely describes the crops, not altering the grammatical number of 'cultivation'.
2
Determine the number (singular or plural) of the subject.
The subject 'cultivation' is singular.
It refers to a single activity, which requires a singular verb form.
3
Select the verb option that matches the subject in number and forms a complete sentence.
The singular verb 'has gained' is correct.
The other options are either plural ('NO CHANGE' / 'have gained' and 'were gaining') or fail to provide a complete predicate ('gaining').

Key Concept

Subject-Verb Agreement with Intervening Modifiers
Question 50Question →

Astronomers today continue to study these cosmic objects. The discovery of pulsars, which are highly magnetized rotating neutron stars, reveal how stars behave at the end of their life cycles.

Which of the following is the correct choice for the underlined portion?

Show answer & explanation

Answer: reveals

Answer

reveals
The correct option is 'reveals' because the subject of the clause is the singular noun 'discovery'. The intervening structures 'of pulsars' and 'which are highly magnetized rotating neutron stars' contain plural nouns that must not affect the verb's agreement. The singular present-tense verb 'reveals' agrees with 'discovery' and aligns with the present-tense context established by the verbs 'continue' and 'behave'.

Step-by-Step Solution

1
Identify the grammatical subject of the clause containing the verb.
The subject is the singular noun 'discovery'. The prepositional phrase 'of pulsars' and the relative clause 'which are highly magnetized rotating neutron stars' both modify 'discovery' but do not change its grammatical number.
Verbs must agree with their actual subject, not with nouns inside modifying phrases or clauses that lie between the subject and the verb.
2
Determine the appropriate tense of the verb from the passage context.
The passage establishes a present-tense timeline using verbs like 'continue' and 'behave'.
Verb tenses must remain consistent unless a shift is logically required by the context.
3
Combine the subject number and verb tense to find the correct form.
A third-person singular, present-tense verb is needed, which is 'reveals'.
Matching both singular agreement and present tense resolves the grammatical error.

Key Concept

Subject-verb agreement requires a verb to agree in number with its grammatical subject. Descriptive elements like prepositional phrases or relative clauses that separate the subject from the verb must be ignored when determining agreement.
Question 51Question →

Read the passage below and write the correct present-tense form of the verb 'to be' in the blank to ensure proper subject-verb agreement.

Fill in the blanks below

A crucial collection of letters written by the nineteenth-century botanist, which contains detailed illustrations of native wildflowers, now available for public viewing at the library.
Show answer & explanation

Answer

is
The singular verb 'is' matches the singular subject 'collection'. The noun 'collection' remains singular despite being followed by the plural modifier 'of letters' and the relative clause containing 'illustrations' and 'wildflowers'.

Step-by-Step Solution

1
Locate the verb blank and trace backward to find the true subject of the clause.
The subject is the noun phrase 'A crucial collection'.
The words following 'collection' are modifying phrases: 'of letters' is a prepositional phrase, 'written by the nineteenth-century botanist' is a participial phrase, and 'which contains...' is a relative clause. None of these modifiers contain the head subject of the sentence.
2
Determine if the subject is singular or plural.
The subject 'collection' is singular.
Even though it refers to a group of items (letters), the noun 'collection' itself is a singular entity.
3
Apply subject-verb agreement rules to select the correct form of 'to be' in the present tense.
The correct verb form is 'is'.
A singular subject ('collection') requires a singular verb ('is') to achieve proper agreement.

Key Concept

Subject-Verb Agreement
Estimated Time:1m 0s
Question 52Question →

Although many people believe that libraries are becoming obsolete in the digital age, recent data suggests otherwise. In fact, a modern library with its extensive digital archives, community workshops, and collaborative workspaces serves as a vital hub for neighborhood interaction.

Which of the following choices is the best replacement for the underlined word?

Show answer & explanation

Answer: NO CHANGE

Answer

NO CHANGE
The singular subject of the sentence is 'library'. The phrase starting with 'with' is a prepositional phrase that modifies the subject but does not change its number. Therefore, the verb must be singular. The present-tense verb 'serves' correctly agrees with the singular subject and maintains the present-tense context established in the rest of the passage.

Step-by-Step Solution

1
Identify the subject of the verb in the sentence.
The subject is 'a modern library', which is singular.
To ensure subject-verb agreement, we must ignore the intervening prepositional phrase ('with its extensive digital archives, community workshops, and collaborative workspaces') and focus only on the main subject.
2
Determine the correct verb form and tense.
The singular present-tense verb 'serves' is required.
The surrounding context uses the present tense ('are becoming', 'suggests'), so the verb must be singular and in the present tense.

Key Concept

Subject-Verb Agreement with Intervening Phrases
Estimated Time:1m 0s
Question 53Question →

The passage below describes subterranean fungal networks in forests. Read the passage and identify the correct present-tense forms of the verbs 'to be' (for the first blank) and 'to depend' (for the second blank) that maintain proper subject-verb agreement. What are the correct verb forms to fill in the blanks?

Fill in the blanks below

Beneath the forest floor, a complex network of fungal threads known as mycelium connects the roots of various plants. This subterranean web of connections, which facilitates the sharing of nutrients and chemical warning signals among different species, essential to the survival of the forest. Indeed, the vitality of the older canopy trees, as well as that of the younger saplings, heavily on this underground exchange.
Show answer & explanation

Answer

The correct verbs are 'is' for the first blank and 'depends' for the second blank.
The correct verbs are 'is' and 'depends' because the subject of the first blank is the singular noun 'web' and the subject of the second blank is the singular noun 'vitality'. In both cases, plural nouns inside intervening phrases ('connections', 'species', 'trees', 'saplings') do not alter the grammatical number of the main subject.

Step-by-Step Solution

1
Identify the subject of the first verb.
The subject is 'web', which is singular.
The singular noun 'web' is followed by the prepositional phrase 'of connections' and a relative clause 'which facilitates the sharing... among different species'. These intervening structures do not change the grammatical number of the subject, which remains singular.
2
Determine the correct form of the verb 'to be' for the first blank.
The correct form is 'is'.
Since the subject 'web' is singular and the context is in the present tense, the third-person singular present form 'is' must be used.
3
Identify the subject of the second verb.
The subject is 'vitality', which is singular.
In the phrase 'the vitality of the older canopy trees, as well as that of the younger saplings', the core subject is 'vitality'. The prepositional phrase 'of the older canopy trees' and the additive phrase 'as well as that of the younger saplings' are parenthetical modifiers and do not affect the singular nature of the main subject.
4
Determine the correct form of the verb 'to depend' for the second blank.
The correct form is 'depends'.
Since the subject 'vitality' is singular and the sentence is written in the present tense, the singular present-tense verb 'depends' is required.

Key Concept

Subject-Verb Agreement
Estimated Time:1m 30s
Question 54Question →

Read the following passage about marine biology. Which present-tense form of the verb 'to provide' correctly completes the sentence to ensure proper subject-verb agreement?

Fill in the blanks below

The analysis of deep-sea hydrothermal vents, which support unique ecosystems in complete darkness, valuable insights into the origins of life on Earth.
Show answer & explanation

Answer

provides
The subject of the sentence is the singular noun 'analysis.' The intervening plural noun 'vents' within the prepositional phrase and 'ecosystems' within the relative clause do not affect the subject's singular number. Therefore, the verb must be the singular 'provides' to achieve correct subject-verb agreement.

Step-by-Step Solution

1
Identify the grammatical subject of the clause.
The subject is the singular noun 'analysis.'
The prepositional phrase 'of deep-sea hydrothermal vents' and the relative clause 'which support unique ecosystems...' are modifiers that separate the subject from the verb but do not change the subject's number.
2
Determine the correct verb number (singular or plural) and tense.
A third-person singular present-tense verb is required.
A singular subject requires a singular verb. The present-tense verb 'support' in the relative clause establishes a present-tense context for the sentence.
3
Select the correct form of the verb 'to provide.'
The singular present-tense form is 'provides.'
The form 'provides' agrees with the singular subject 'analysis' and maintains consistent present tense.

Key Concept

Subject-Verb Agreement with Intervening Phrases
Question 55Question →

The dynamic interactions between a host organism and its gut microbiome, which consists of trillions of microscopic bacteria, helps regulate the host's metabolic functions. This complex symbiotic relationship influences everything from nutrient absorption to immune system development.

Which choice is the most grammatically correct replacement for the underlined word?

Show answer & explanation

Answer: help

Answer

The correct verb form is the plural present-tense 'help' because the subject of the sentence, 'interactions', is plural.
The correct choice is the plural verb 'help' because the subject of the verb is the plural noun 'interactions'. Modifying elements like 'between a host organism and its gut microbiome' and 'which consists of trillions of microscopic bacteria' separate the subject from the verb but do not affect the agreement.

Step-by-Step Solution

1
Locate the grammatical subject of the clause.
The subject is the plural noun 'interactions'.
The verb must agree in number with this main noun rather than any nearby nouns.
2
Identify and temporarily ignore any intervening modifier phrases or clauses between the subject and the verb.
The prepositional phrase 'between a host organism and its gut microbiome' and the relative clause 'which consists of trillions of microscopic bacteria' both modify 'interactions' but do not change its plural nature.
Nouns within modifying phrases (like 'microbiome' or 'organism') cannot function as the subject of the main verb.
3
Select the verb form that matches the plural subject and respects the established tense of the passage.
The plural present-tense form 'help' matches the plural subject 'interactions' and maintains consistency with other present-tense verbs in the passage like 'consists' and 'influences'.
This avoids both subject-verb agreement errors and unnecessary tense shifts.

Key Concept

Subject-verb agreement requires a plural subject to take a plural verb, even when separated by intervening modifying phrases or clauses.
Question 56Question →

The passage below discusses the acoustic properties of ancient Greek theatres. Read the passage and determine the correct present-tense form of the verb 'to allow' to complete the sentence. What is the correct form of the verb?

Fill in the blanks below

The acoustic clarity of ancient Greek theatres, which stems from the precise arrangement of limestone seats, actors' voices to carry all the way to the back rows without amplification.
Show answer & explanation

Answer

allows
The subject of the main clause is the singular noun 'clarity'. The intervening elements—the prepositional phrase 'of ancient Greek theatres' and the relative clause 'which stems from the precise arrangement of limestone seats'—do not affect the subject's number. Therefore, the singular verb 'allows' is required to maintain subject-verb agreement.

Step-by-Step Solution

1
Identify the subject of the sentence.
The grammatical subject of the main clause is 'clarity' (specifically 'The acoustic clarity').
The prepositional phrase 'of ancient Greek theatres' and the parenthetical relative clause 'which stems from the precise arrangement of limestone seats' are modifiers that separate the subject from the main verb and do not change the grammatical number of the subject.
2
Determine the grammatical number of the subject and select the corresponding verb form.
The noun 'clarity' is singular, so it requires the third-person singular present-tense verb 'allows'.
A singular subject must agree with a singular verb form (ending in '-s' in the present tense) to ensure correct subject-verb agreement.

Key Concept

Subject-Verb Agreement
Question 57Question →

Read the passage and answer the question that follows.

Deep-sea sediment cores retrieved from the Arctic Ocean contain microscopic fossils of marine organisms known as foraminifera. The chemical composition of these fossils, which accumulated on the ocean floor over millions of years, help scientists reconstruct past global temperatures. By analyzing the oxygen isotopes within the shells, researchers can determine the extent of prehistoric ice sheets.

Which of the following is the best revision of the underlined portion?

Show answer & explanation

Answer: helps

Answer

The singular present-tense verb 'helps' is correct because it agrees with the singular subject 'composition'.
The singular present-tense verb 'helps' is correct because it matches the singular subject 'composition'. The plural nouns 'fossils' and 'years' are parts of modifying prepositional and relative clauses and do not affect the grammatical number of the subject.

Step-by-Step Solution

1
Identify the subject of the clause containing the underlined verb.
The subject is 'composition', which is a singular noun.
The verb must agree in number (singular vs. plural) with its true grammatical subject, not with the nouns inside intervening phrases.
2
Identify and ignore intervening phrases and clauses that separate the subject from the verb.
The prepositional phrase 'of these fossils' and the relative clause 'which accumulated on the ocean floor over millions of years' both contain plural nouns ('fossils', 'years'), but they do not change the singular nature of the subject 'composition'.
Intervening modifier phrases do not affect subject-verb agreement.
3
Determine the correct verb form and tense based on the subject and the surrounding context.
A singular, present-tense verb ('helps') is required to agree with 'composition' and match the present-tense timeline established by 'contain' and 'can' in the surrounding sentences.
Using a plural verb or shifting to the past tense would violate rules of agreement and tense consistency.

Key Concept

Subject-Verb Agreement with Intervening Phrases
Estimated Time:1m 0s
Question 58Question →

The restoration of medieval stained glass windows requires a delicate balance of art and chemistry. The accumulation of dirt, pollutants, and fungal growth on the glass surface have threatened to obscure the vibrant colors permanently. Conservators must carefully clean the panels before applying a protective microcrystalline wax coating.

Which option correctly completes the underlined portion of the passage?

Show answer & explanation

Answer: has threatened

Answer

has threatened
The singular verb 'has threatened' is correct because it agrees in number with the singular subject 'accumulation'. The plural nouns 'dirt', 'pollutants', and 'growth' are objects of the preposition 'of' and do not determine the number of the verb. This choice also maintains present-tense consistency with the surrounding text.

Step-by-Step Solution

1
Identify the grammatical subject of the sentence containing the underlined verb.
The subject is the singular noun 'accumulation'. The plural nouns 'dirt', 'pollutants', and 'growth' are part of the intervening prepositional phrase 'of dirt, pollutants, and fungal growth' and do not affect the verb's agreement.
The subject of a sentence is never found within a prepositional phrase.
2
Select the verb form that agrees with the singular subject and matches the tense of the passage.
The singular present perfect verb 'has threatened' agrees with the singular subject 'accumulation' and maintains consistency with the present tense of the rest of the passage ('requires', 'must').
A singular subject requires a singular verb, and tenses should remain consistent across sentences unless there is a clear temporal shift.

Key Concept

Subject-Verb Agreement with Intervening Phrases
Question 59Question →

The following sentence contains a blank. Complete the sentence by writing the correct present-tense form of the verb 'to represent' in the blank, ensuring proper subject-verb agreement.

Fill in the blanks below

The discovery of ancient silk scrolls, which were buried in the dry climate of the desert tomb for over two millennia, a major breakthrough for historians studying the Han dynasty.
Show answer & explanation

Answer

represents
The singular verb 'represents' correctly agrees with the singular subject 'discovery'. All intervening words between the subject and the verb are parts of modifying prepositional phrases and relative clauses, which do not change the grammatical number of the subject.

Step-by-Step Solution

1
Identify the main subject of the clause.
The subject is 'discovery'.
Intervening modifiers like the prepositional phrase 'of ancient silk scrolls' and the relative clause 'which were buried in the dry climate of the desert tomb for over two millennia' do not affect the verb's agreement.
2
Determine the grammatical number of the subject.
The noun 'discovery' is singular.
It refers to a single act of finding the scrolls.
3
Determine the correct present-tense form of the verb 'to represent' to match the singular subject.
The singular third-person present-tense form is 'represents'.
Singular subjects require singular verbs ending in '-s' in the present tense.

Key Concept

Subject-Verb Agreement
Question 60Question →

Read the sentence below. Which form of the verb in parentheses correctly completes the sentence to maintain proper subject-verb agreement?

Fill in the blanks below

The seasonal migration of monarch butterflies, which spans thousands of miles across North America, (intrigue) researchers studying insect navigation.
Show answer & explanation

Answer

intrigues
The correct form is 'intrigues'. The subject of the sentence is the singular noun 'migration'. The prepositional phrase 'of monarch butterflies' and the relative clause 'which spans thousands of miles across North America' are intervening modifiers that do not affect the subject's number. A singular subject requires a singular verb, which in the present tense is 'intrigues'.

Step-by-Step Solution

1
Identify the main subject of the clause containing the verb to be filled.
The subject is the singular noun phrase 'The seasonal migration'.
The plural nouns 'butterflies' and 'miles' are part of intervening phrases ('of monarch butterflies' and 'which spans thousands of miles') and do not function as the subject of the main verb.
2
Determine the number of the subject (singular or plural).
The subject 'migration' is singular.
Finding the head noun of the subject phrase shows it is singular, meaning it requires a singular verb.
3
Select the correct present-tense singular form of the verb 'intrigue'.
The correct form is 'intrigues'.
In the present tense, third-person singular verbs end in '-s'.

Key Concept

Subject-verb agreement requires a singular verb for a singular subject, even when intervening prepositional phrases or relative clauses contain plural nouns.
Estimated Time:45s
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